Cutting tool



May 9, 1944. "L, Q OAK Em 2,348,262

CUTTING TOOL Filed sept. '7, 1942 Patented May 9, 1944 CUTTING TOOLLawrence C. Oak, Huntington Woods, and James B. Donnelly, Detroit,Mich.,

assignors t Ternstedt Manufacturing Company, Detroit, Mich., acorporation of Michigan l Application September 7, 1942, SerialNo.l1.57.5941

7 Claims.v (Cl. ,2S-95.)

The invention relates to cutting tools and especially to tools of thekind used in lathes for turning.

In the pastsuch tools have consisted of a piece of steel of suitabledimensions with its tip ground to provide a cutting edge of the desiredcontour and adapted to be held in the tool post of a lathe, planer, orother machine. As the cutting edges of such tools become worn or areotherwise destroyed, they are renewed by 1re-grinding the tip and thisprocess can be repeated as often as necessary so long as the length ofstock remaining in the tool is sufcient.

More recently, materials such as tungsten carbide which will .maintain acutting edge for a longer time than ordinary steel have been discovered,but since these materials are much more expensive than ordinary steel ithas been the practice to cement, braze or weld a bit of the material ina suitably formed recess at the tip of a piece of ordinary steel formingthe tool shank and grind the tipped end of said shank to provide thecutting edge in the tip of more durable material.

However, when the tool thus formed has been re-ground several times andthe more durable material and part of the shank of ordinary steel hasbeen thus expended, the remaining portion of the shank has beendiscarded as useless-a practice which is extremely wasteful.

The object of the invention is a tool shank provided with a bit which issuitably secured as by welding or brazing to a backing piece which isadjustable, detachable and renewable on a tool shank which may be usedindenitely.

The above and other objects of the invention will be apparent as thedescription proceeds.

In the drawing Figure l shows tools according to the invention in toolposts adjusted to perform different cutting operations on a work piece.

Figure 2 is an enlarged plan View of an end of one of the tools shown inFigure 1.

Figure 3 is a plan view of the end of the tool shank with the bit andbacking piece assembly removed.

Figure 4 is a sectional view of line 4-4 of Figure 2.

Figure 5 is a sectional view on line 5-5 of Figure 2.

The tools I, 2, and 3 of Figure l are identical, except that the cuttingedge of the tool 2 is ground to a different shape than the tools I and3. They are mounted in identical tool posts 1, 8, and 9 which areadjustable as shown to perform the various indicatedfcutting operationson a work piece I0. Y u

Referring now more particularly t0 Figures 2-5, each o f the tools ofFigure 1 comprises a Shank portion I2, and a backing piece I4 with a bitI6 of more durable material than the backing piece I4 or the shank I2.The bit IS is welded, brazed, or otherwise rigidly secured in a recessedpart I'! of the backing piece I4 which in turn seats on a recessed partI9 of the shank l2.

The surface of the recessed part I9 of the shank I2 isV provided withregularly spaced serrations in three directions; transversely as shownin Figure 4 and as indicated by the broken lines in the tool I of Figurel, and diagonally as respectively indicated by the broken lines in thetools 2 and 3 of Figure 1. Together the serrations in these diierentdirections form the pattern shown in Figure 3. The bottom surface of thebacking piece I4 is similarly serrated to match the serrated surface onthe shank I2, and when these parts are clamped together with theserrations in interengaging relationship, a thrust in any directionwhich might otherwise cause relative sliding displacement thereof iseffectively resisted by the surfaces of the serrations.

A key 30 secured by a screw 3l in a slot 32 in the recessed part I 9 ofthe shank I2 engages a longitudinal groove 33 in the bottom surface ofthe backing piece I4 and prevents other than longitudinal adjustingmovement thereof relatively to the shank I2 in steps equa1 to one ormore times the pitch of the interengaging serrations.

The backing piece I4 with its bit I6 is rigidly clamped and secured tothe shank I2, in the desired position of longitudinal adjustment by setscrews 34 and 35 which extend through longitudinally slotted orotherwise elongated and countersunk holes 3l and 3B in the shank I2,into tapped holes in the backing piece. The maximum extent of adjustmentthus provided is limited by the length of the elongated holes 31 and 38,and as shown in Figure 4 is from the position shown in full lines to theposition shown in dotted lines therein.

A tool according to the invention has the following advantages: There iseconomy of steel because only one shank per operation per machine, needbe provided, and it lasts indenitely. There is a saving of heat inbrazing the bit to the backing piece since the latter is a much smallerpiece to be heated than a whole shank. Since only the cutting bit andbacking piece has to be ground there is a saving of material andgrinding time. Because only the cutting bit and backing piece has to berenewed, the inventory is re- Y justably securedtogsaid shank, in whichsaid' means include a tapped holel in said backing pieceVa shank, a holein said shank, and a set screw extending through said hole in said shankinto said tapped hole in the backing piece for securing said partstogether, there being clear-f ance between said set screw and the Wallof the hole in the shank to permit adjustment in the position of saidcutting bit and backing piece relatively t the shank.

2. In a cutting tool, a cutting bit, a backing piece therefor, saidcutting bit being rigidly secured to said backing piece, a tapped holein said backing piece, a shank, a hole in said shank, a set screwextending through said hole in said shank into said tapped hole in thebacking piece for securingsaid parts together, there beingclearancebetweenlsaid set'screw and the wall of the hole in the shank topermit adjustment in the position of vsaid cutting bit and backing piecerelatively to the shank, and means additional to said-,'st screwforpreventing undesired relative displacement of said parts. Y

3. The combination according to claim 2 in which said Vmeans consist ofmatching serrations on the engaging surfaces of said backing pieceands'hank.

4. The combinationv according to claim 2 in which said means consist ofintengaging multi-r directional serrations on the engaging surfaces ofsaid backing piece and shank to prevent undesired relative displacementthereof in any direction.

5. 'I'he combination according to claim 2 in which the hole in saidshank is longitudinally elongated to permit adjustment of lsaid cuttingbit and backingv piece longitudinally of the shank.

6. The combination according to claim 2 in which the hole in said shankis longitudinally elongated to permit adjustment of said cutting vbitand backing piece longitudinally of the shank,

, andv a longitudinally disposed key between said parts preventsrelative displacement of said parts in any other direction.

7. In a cutting tool, a cutting bit, a backing piece with a recessedpart, said cutting bit being permanently secured in the recessed part ofsaid backing piece, a tool shank, a recessed part in said tool shank toaccommodate said cutting bit and backing piece, a tapped hole in saidbacking piece, a longitudinally elongated hole in said shank, a setscrew extending through said longitudinally elongated hole in said shankand into the said tapped hole in the backing piece for securing saidparts together in different positions ofv relative longitudinaladjustment, and means additional to said set screw for preventingundesired relative longitudinal displacement of said backing piece andshank comprising interengaging transverse serrations in the bottomsurface of said backing piece andthe bottom of the recess in the shank.A

LAWRENCE C. OAK. JAMES B. DONNELLY.

